: I'm building a very small cabin that will be used only a few times per year. It will be used by only my wife and I. I looked at drywells and they looked relatively easy to install myself, but do I have to use them with a septic tank? If so, what size?Answer; It would be best to check with the local building authorities (the one that issued your "Bldg. Permit"? They will advise as to the size and procedure. (protect the enviroment)...Hube